The light novel for JSDF's activity in that world is already over. The author already started his work on JMSDF, Japan's Self Defense Navy. The sequel to this. New characters, new modus operandi, and new location on that other world. Afai can tell, it involves
Japan being the sole client on Gate travel that is entirely operated by the Alnus Community, namely the sorceress that have the Goddess hair.
and
Japan spending more on new "resources" acquisition by sending a fucking submarine to prowl the waters of the new world. There will be pirates and new harem
Stupid shit asking stupid question to an answer you can read in plain sight deserve a rude reply. If you cannot handle people calling you stupid, log off.
Imagine showing this to yourself reading the first 20 chapters and saying "Yeah, this is GATE."
Huh? Japan? Modern military? Itami? Nah bro, you hit your head, it's medieval fantasy with a bit of magic.